Pomegranates help purify pharmaceuticals in wastewater

  • 19 May 2023
  • 2 minute read
  • Words Natasha Wiseman
Pomegranate extract was use in the research. Image: Jonas Renner / Unsplash

Researchers from Stockholm University have developed porous crystals made from pomegranate extract to capture and degrade pharmaceutical molecules in municipal wastewater.

Pharmaceutical compounds affect the human body to improve our health, but they can also have unintentional adverse effects for the wellbeing of wildlife. That is why wastewater treatment plants are seeking to remove emerging organic contaminants (EOCs), including active pharmaceutical ingredients

New materials and technologies are now required to do this work in an efficient and affordable way. One strategy for removing pollutants from water is by using porous materials that behave like sponges.

“We got the opportunity to work directly with water samples from the treatment plant, thereby finding an application where our material could be put to use towards a very pressing environmental issue."

Erik Svensson Grape, University of Stockholm

Metal-organic frameworks (MOFs) are a type of nanoporous material, comprising pores 100nm or smaller, made of metal ions and organic molecules. Most MOFs are made using synthetic organic molecules, but now researchers from the department of materials and environmental chemistry at Stockholm University have developed new porous MOFs using a naturally occurring molecule found in plants – including pomegranates - ellagic acid.

Erik Svensson Grape with a model of the new material which degrades pharmaceutical residues. Image: Lisa Munthe

“Ellagic acid is one of the main building units of naturally occurring polyphenols known as tannins, which are common in fruits, berries, nuts, and tree bark," says aptly named PhD student Erik Svensson Grape. "By combining ellagic acid, which was extracted from either pomegranate peel or tree bark, with zirconium ions, we developed a new highly porous MOF which we named SU-102.”

In order to test the performance of SU-102, water that had already been purified at a local wastewater treatment facility was further treated with the new MOF. The results showed that SU-102 removed many of the pharmaceutical pollutants that were not fully removed by the wastewater treatment facility.

Electron microscope image showing part of an SU-102 crystal - the dark areas are tiny pores 1nm wide. Image: Tom Willhammar

In addition to capturing the pharmaceutical pollutants, SU-102 was also used to break down pollutants using light in a process known as photodegradation.

“This has been a very exciting project as we got the opportunity to work directly with water samples from the treatment plant, thereby finding an application where our material could be put to use towards a very pressing environmental issue. We hope one day that SU-102 will be used on a bigger scale and also for other environmental applications,” said Grape.

The research is published in the scientific journal Nature Water.